Endocrine Abstracts

Introduction: Amiodarone is a well-established antiarrhythmic drug frequently used in tachyarrhythmias. Side effects include hypothyroidism and hyperthyroidism. Extreme cases such as myxedematous and thyrotoxic crisis are very uncommon. Here we report one case of each of these presentations.

Case Report no.1: A 73-year-old woman with history of atrial fibrillation under treatment with amiodarone presented to the emergency department with headache, nausea and chest pain. On admission, she was tachycardic - atrial fibrillation with heart rate of 127 bpm. Her free T4 (fT4) and TSH were 31.5 ρmol/l and <0.01 mU/l, respectively and her antithyroid antibodies were all negative. Thyroid ultrasound demonstrated a micronodular gland with increased Doppler sign. Amiodarone was discontinued and she was started on propylthiouracil, propranolol, hydrocortisone, cholestyramine and Lugol’s iodine, without laboratorial or clinical improvement - sustained tachycardia and coma. As such she was thyroidectomized. Her thyroid function tests and heart rate improved, however she died due to sepsis secondary to MRSA on the 18th post-operative day.

Case Report no.2: A 90-year-old woman with history of atrial fibrillation under treatment with amiodarone presented to the emergency department with a 12-h history of diminished consciousness level. On admission, she was myxedematous, hypothermic, bradycardic and with bradypnea. Laboratory studies revealed respiratory acidemia, increased creatinine, toxic benzodiazepine levels, TSH 80.2 mU/l and fT4 4.47 ρmol/l (antithyroid antibodies were negative). She was started on IV fluids, non-invasive ventilation and antibiotherapy due to suspected pneumonia. Amiodarone was discontinued and IV L-thyroxine (250 μg) and hydrocortisone (200 mg) were administered and continued orally on the following days. She showed dramatical clinical improvement and was discharged after 10 days on oral L-thyroxine 75 μg/day.

Conclusion: Although uncommon, extreme cases of thyroid dysfunction can occur in patients on amiodarone therapy, underlining the importance of thyroid function monitoring.